Method for coating substrates with improved substrate preheating and substrate preheating device

ABSTRACT

In the method for coating substrates the substrates are placed in recesses in a glass-ceramic plate or plates arranged over infrared high-temperature radiators with the surfaces to be coated on the radiators. The substrates are heated from below to the process temperature required for the coating. Subsequently the substrates are removed from the heating device, introduced into a coating chamber and coated. The preheating device for the substrates has two glass-ceramic plates that are placed loosely on top of each other and infrared high-temperature radiators. Substrate receptacles are provided in the glass-ceramic plates by approximately coincident recesses of different size in the plates so that the substrates can be held in close proximately to the radiators during the preheating.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an improved device forpreheating substrates for a coating process that requires preheating ofthe substrates. It also relates to an improved coating method in whichsubstrate preheating is required. The invention also relates to anexternal preheating of the substrates.

[0002] U.S. Pat. No. 5,976,258 discloses an apparatus for processingsubstrates. The apparatus contains a component for heating of thesubstrates to an elevated temperature. The substrate is pre-heated thereand then transported or conveyed for further processing.

[0003] Substrate holders with recesses are disclosed in U.S. Pat. No.4,350,578, U.S. Pat. No. 5,137,610 and JP-A-01-255671.

[0004] In the conventional method for preheating substrates, especiallyglass parts, prior to coating them, the preheating is energy-intensiveand time-consuming.

SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide an improvedcoating process in which preheating of the substrates to be coated isrequired.

[0006] It is another object of the present invention to provide animproved economic, environmentally friendly method for preheatingsubstrates to be coated in a coating process.

[0007] It is a further object of the present invention to provide aheating device for preheating substrates for a coating process requiringpreheating of the substrates.

[0008] The method according to the invention of coating a substrate inwhich preheating of the substrate is required comprises the steps of:

[0009] a) providing a device for heating the substrate, which includesat least one heat-producing component and at least one glass-ceramicplate, wherein the at least one glass-ceramic plate is provided with atleast one recess and the substrate fits in the at least one recess so asto be on said at least one heat-producing component;

[0010] b) placing the substrate in the at least one recess so that asurface of the substrate to be coated is placed on the at least oneheat-producing component;

[0011] c) heating the substrate from below to a process temperaturerequired for the coating with the at least one heat-producing component;and

[0012] d) removing the substrate from the device for the heating andthen placing the substrate in a coating chamber; and subsequently

[0013] e) coating the substrate in the coating chamber.

[0014] The heating device according to the invention for preheating thesubstrates considerably shortens the time required for coating thesubstrate. The overall process including coating and preheating savesenergy. The preheating reduces wear of the coating device. Thepreheating of the substrate is more uniform when the preheating deviceaccording to the invention is used. The quality of the coating isimproved in the coating process according to the invention. Thetemperature adjustment required can be implemented without influencingthe process time. The coating process according to the inventionfacilitates stable process management.

[0015] In a preferred embodiment of the invention the heating deviceincludes at least one heat-producing component and at least oneglass-ceramic plate. The at least one glass-ceramic plate is providedwith at least one recess in which the substrate fits or which matchesthe substrate. Because of its low thermal conductivity, theglass-ceramic material is preferred for the plate or plates.

[0016] A preferred embodiment of the heating device according to theinvention has two glass-ceramic plates, which are laid loosely on top ofone another, and have correspondingly different recesses with differentsized openings arranged approximately over each other. The approximatelycoincident recesses in the respective plates provide substratereceptacles. When the heating device comprises the two glass-ceramicplates, heat losses are correspondingly reduced. The production of thesubstrate receptacles is made easier.

[0017] In a preferred embodiment of the coating method according to theinvention during the preheating of the substrates the internaltemperature of the heating device is from 500° C. to 800° C. Goodresults are achieved within this temperature range. According to anotherpreferred embodiment of the method at least one coating layer isprovided on the substrate to be coated by the coating method.

[0018] According to various embodiments of the coating method of theinvention, the coating of the substrates is performed by at least one ofthe following processes: CVD (chemical vapor deposition), PVD (physicalvapor deposition), PECVD (plasma-enhanced chemical vapor deposition),PICVD (plasma impulse chemical vapor deposition), LPCVD (low-pressurechemical vapor deposition) or TCVD (thermal chemical vapor deposition).

[0019] In a preferred embodiment of the device according to theinvention the heat-producing components are infrared high-temperatureradiators. These high-temperature radiators have a longer service life.

[0020] Glass substrates are especially preferred as the substrates.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0021] The objects, features and advantages of the invention will now bedescribed in more detail with the aid of the following description ofthe preferred embodiments, with reference to the accompanying figures inwhich:

[0022]FIG. 1 is a perspective view of the device for preheatingsubstrates for a coating process according to the invention includingtwo glass-ceramic plates; and

[0023]FIG. 2 is a perspective view showing a substrate receptaclecomprising different sized recesses in the two glass-ceramic plates ofthe device of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The heating device 1, which is shown in FIG. 1, for preheatingthe glass substrates includes heat-producing components 3 and twoglass-ceramic plates 2,2′ with recesses 4,4′ for the substrates. Theheat-producing components 3 are advantageously infrared high-temperatureradiators, which are operated to produce an interior temperature of 500°C. in the heating device. The upstream heating resulted in 5300 partsper hour being coated.

[0025] In contrast, in a conventional method, in which the substrateswere heated in a coating installation, it was possible to coat 3200pieces per hour in a comparative example corresponding to the example ofthe above paragraph. A comparison between the example of the inventionand the comparative example demonstrates that, using the coating processaccording to the invention, the yield of coated substrates has risen by65%. The energy consumption for heating was 50% lower.

[0026] The figures show an inventive heating device for heatingsubstrates for a coating process.

[0027] The heating device 1 for preheating the glass substrates, whichis shown in FIG. 1, comprises two glass-ceramic plates 2,2′, which arelaid loosely over each other, and which cover the heating-producingcomponents 3. The glass-ceramic plates 2,2′ are provided with recesses4,4′, which are matched to or fit the substrates, which have differentsized openings as shown in FIG. 2. The recesses 4,4′ advantageouslyprovide a substrate receptacle H. The recesses 4,4′ have different sizedopenings 4,4′. The heat-producing components 3 arranged in the innerregion of the heating device 1 are infrared high-temperature radiators.

[0028] The disclosure in German Patent Application 101 25 675.2 of May25, 2001 is incorporated here by reference. This German PatentApplication describes the invention described hereinabove and claimed inthe claims appended hereinbelow and provides the basis for a claim ofpriority for the instant invention under 35 U.S.C. 119.

[0029] While the invention has been illustrated and described asembodied in a method for coating a substrate with improved substratepreheating and improved substrate preheating device, it is not intendedto be limited to the details shown, since various modifications andchanges may be made without departing in any way from the spirit of thepresent invention.

[0030] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention.

[0031] What is claimed is new and is set forth in the following appendedclaims.

We claim:
 1. A method of coating a substrate in which preheating of thesubstrate is required, said method comprising the steps of: a) providinga device for heating said substrate, said device comprising at least oneheat-producing component and at least one glass-ceramic plate, whereinsaid at least one glass-ceramic plate is provided with at least onerecess and said substrate fits in said at least one recess so as to beon said at least one heat-producing component; b) placing said substratein said at least one recess so that a surface of said substrate to becoated is arranged on said at least one heat-producing component; c)heating said substrate from below to a process temperature required forthe coating with said at least one heat-producing component; and d)removing said substrate from the device for the heating and then placingsaid substrate in a coating chamber; and subsequently e) coating thesubstrate in the coating chamber.
 2. The method as defined in claim 1,wherein the device for the heating includes a substrate receptacle forholding the substrate comprising said at least one recess provided inthe at least one glass-ceramic plate.
 3. The method as defined in claim1, wherein the device for the heating has an interior temperature of500° C. to 800° C. during the heating of the substrate.
 4. The method asdefined in claim 1, wherein said substrate is provided with at least onecoating layer during said coating.
 5. The method as defined in claim 1,wherein said coating takes place by means of at least one of a chemicalvapor deposition process, a physical vapor deposition process, aplasma-enhanced chemical vapor deposition, a plasma impulse chemicalvapor deposition, a low-pressure chemical vapor deposition and a thermalchemical vapor deposition process.
 6. The method as defined in claim 1,wherein said substrate is made of glass.
 7. A method of coatingsubstrates in which preheating of the substrates is required, saidmethod comprising the steps of: a) providing a device for heating saidsubstrates, said device comprising a plurality of heat-producingcomponents and at least two glass-ceramic plates placed loosely on topof each other, wherein said glass-ceramic plates are provided with aplurality of recesses for said substrates and said substrates fit in ormatch said recesses so as to be on said heat-producing components; b)placing said substrates in said recesses so that surfaces of saidsubstrates to be coated are arranged on said heat-producing components;c) heating said substrates from below to a process temperature requiredfor the coating with said heat-producing components; and d) removingsaid substrates from the device for the heating and then placing saidsubstrates in a coating chamber; and subsequently e) coating thesubstrates in the coating chamber.
 8. The method as defined in claim 7,wherein the device for the heating of the substrates has an interiortemperature of 500° C. to 800° C. during the heating of the substrates.9. The method as defined in claim 7, wherein said substrate is providedwith at least one coating layer during said coating.
 10. The method asdefined in claim 7, wherein said coating takes place by at least one ofa chemical vapor deposition process, a physical vapor depositionprocess, a plasma-enhanced chemical vapor deposition, a plasma impulsechemical vapor deposition, a low-pressure chemical vapor deposition anda thermal chemical vapor deposition process.
 11. The method as definedin claim 7, wherein said substrate is made of glass.
 12. A device forpreheating a substrate for coating said substrate, said devicecomprising a plurality of heat-producing components and at least twoglass-ceramic plates placed loosely on top of each other, wherein saidglass-ceramic plates are provided with a plurality of recesses for saidsubstrates and said substrates fit in or match said recesses so as to beon said heat-producing components.
 13. The device as defined in claim12, further comprising respective substrate holders for holding saidsubstrates and wherein said substrate holders comprise at least anapproximately coincident pair of said recesses in said plates.
 14. Thedevice as defined in claim 12, wherein said heat-producing componentscomprise infrared high-temperature radiators.